1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member and a manufacturing method therefor, a process cartridge and an electrophotographic apparatus each including the electrophotographic photosensitive member, and a phthalocyanine crystal and a method producing therefor.
2. Description of the Related Art
An electrophotographic photosensitive member to be used in an electrophotographic apparatus such as a copying machine or a laser beam printer is required to have sufficient sensitivity to image exposure light. It has been known that an azo pigment and a phthalocyanine pigment, each of which is used as a charge generating material for the electrophotographic photosensitive member, exhibit high sensitivity to light having wavelengths in a wide range.
In addition, in recent years, there has been a demand for an increase in image quality as typified by colorization. Due to the colorization, the number of halftone images and solid images as found in photographs is increasing, and the image quality thereof never stops improving. In the case of a color printer and a color copying machine, the acceptable range with respect to a so-called positive ghost image or the like is becoming significantly narrow as compared to the acceptable range of a black-and-white printer and a black-and-white copying machine. The positive ghost image refers to a phenomenon in which the density of only a portion of one image irradiated with light becomes high in a halftone image in the next rotation. The ghost image is considered to be caused as follows. A hole that is one of carriers generated from the charge generating material used in the electrophotographic photosensitive member is injected into a charge transport layer, and thereafter, an electron is liable to remain in a charge generating layer to serve as a memory.
Japanese Patent Application Laid-Open No. H07-331107 discloses a hydroxygallium phthalocyanine crystal having a feature of containing at least one polar organic solvent selected from a compound having an amide group, a compound having a sulfoxide group, and an organic amine.